The present invention relates to antibodies, compositions and methods for diagnosing and treating inflammation. More particularly, the present invention relates to the use of scavenger receptor inhibitors in treatment of an inflammatory response and to methods of diagnosing an inflammatory response via detection of autoantibodies directed at scavenger receptors.
Inflammation is a physiological condition characterized in the acute form by the classical signs of pain, heat, redness, swelling and loss of function. Inflammation often accompanies diseases such as Multiple Sclerosis (MS), osteoarthritis, Inflammatory Bowl Disease (IBD) including Crohn's disease and ulcerative colitis, Rheumatoid Arthritis (RA), SLE, type I diabetes (IDDM), atherosclerosis, encephalomyelitis, Alzheimer's disease, stroke, traumatic brain injury, Parkinson's disease, septic shock and others. In most cases, there is no effective cure for inflammation associated with such disease and existing treatments are palliative and largely fail to control the underlying causes of tissue degradation.
Scavenger receptors (SRs) are cell surface proteins, which are typically found on macrophages and bind various types of chemically modified lipoproteins (1-3), such as low-density lipoprotein (LDL). This family of trans-membrane receptors which are highly varied in structure are involved in receptor-mediated endocytosis, phagocytosis of apoptotic cells and bacteria, as well as in cell adhesion [Peiser L. et al., Curr. Opin. Immun. 14(1):123-128, 2002]. Since the massive receptor-mediated uptake of cholesterol from modified LDL can convert cultured macrophages into cholesteryl ester-filled foam cells, similar to those found in atherosclerotic plaques, it has been postulated that these receptors also function in deposition of LDL cholesterol of macrophages in artery walls during the initial stages of atherosclerotic plaque formation [1].
Scavenger receptors (SRs) are termed as such since they mediate the binding of remarkably wide variety of polyanionic ligands [e.g., modified proteins, sulfated polysaccharides and certain polynucleotides [1, 3, 4]. This property led to the hypothesis that these receptors form a part of an in innate immune response by serving as pattern recognition receptors that bind a wide variety of pathogen components [2-5].
SR-B1 (also referred to as SR-BI or CLA-I) is a macrophage scavenger molecule and a receptor for high-density lipoprotein (HDL) [2, 3, 6, 7] that mediates cholesterol uptake from cells [Rigotti A. et al., Curr. Opin. Lipidol., 8:181-8, 1997; Rigotti A. et al., Proc. Natl. Acad. Sci., 94:12610-5, 1997]. SR-BI can also serve as a receptor for non-HDL lipoproteins and appears to play an important role in reverse cholesterol transport. In vivo experiments showed that this receptor is important for HDL metabolism in mice, and for the metabolism of LDL and HDL cholesterol in humans [Stang H. et al., J. Biol. Chem. 274:32692-8., 1999; Swarnakar S. et al., J. Biol. Chem. 274:29733-9., 1999]. Studies involving the manipulation of SR-B1 gene expression in mice, indicate that its expression protects against atherosclerosis [Kozarsky K. F., and Krieger M., Curr. Opin. Lipidol. 10:491-7., 1999; Ueda Y. et al., J. Biol. Chem. 275:20368-73., 2000; Acton S. L. et al., Mol. Med. Today 5:518-24., 1999]. It was also suggested that HDL and particularly its protein fraction Apo-A1 affect the in vitro production of pro-inflammatory mediators by macrophages (8). Among mediators derived from macrophages that propagate inflammation are interleukin 12 (IL-12), TNF-α and possibly IL-6 whereas, TGF-β and IL-10 have predominantly anti-inflammatory effects [Kiefer R. et al., Prog. Neurobiol. 64(2):109-27, 2001].
PCT Publication No. WO 2004/041179 teaches targeting of scavenger receptor SR-B1 (Cla-I) for the treatment of infection, sepsis and inflammation. This prior art teaches primarily targeting SR-B1 using amphipathic peptides which compete the amphipathic helices in apoliprotein ligands of SR-B1. PCT Publication No. WO 2004/041179 does not provide experimental results for treating autoimmune diseases such as IBD and multiple sclerosis by down-regulating activity or expression of SR-B1, nor does it teach the use of oligonucleotide technology (e.g., antisense, siRNA) and DNA vaccination for targeting SR-B1 and treating inflammatory diseases.
There is thus, a widely recognized need for and it would be highly advantageous to have novel agents and methods using same for targeting SR-B1 and treating inflammatory diseases.